Health
Advisory
EVIDENCE OF WEST NILE VIRUS IN DELAWARE

The Delaware Division of Public Health (DPH) would like to alert the medical community of evidence of West Nile Virus (WNV) in Delaware.
To date, there have been no confirmed cases in humans in Delaware this season. However, two cases have been confirmed in chickens as part
of Delaware’s sentinel surveillance system. Additionally, seven wild birds have tested positive since July 8, 2012.

Approximately 80 percent of all people infected by WNV experience no symptoms. About 20 percent of those who become ill with WNV
typically have mild symptoms. Less than 1 percent of humans infected with WNV develop more serious symptoms which can result in long term
health effects or death. Infection should be considered in adults 50 years of age or older who have onset of unexplained encephalitis or
meningitis in late summer or early fall. The local presence of WNV enzootic activity or other human cases of WNV infection should further
raise the index of suspicion.

WNV in Delaware

West Nile virus first appeared in Delaware birds and horses in 2000. Delaware’s first confirmed human case of West Nile virus
occurred in 2002. In 2003, 17 human cases were confirmed, including two deaths. While there were no reported human cases in 2004, 2006,
and 2009, two cases were confirmed in 2005 and one in 2007, 2008 and 2011.

DPH Diagnostic Testing

The DPH Laboratory (DPHL) performs WNV testing for humans, birds and horses. Methods include antibody testing, as well as Polymerase
Chain Reaction (PCR) and culture. In humans, the preferred specimen is cerebrospinal fluid (CSF). CSF should be collected within 8 days
of illness onset, while serum specimens should be collected within 8-14 days of illness onset. False positive antibody results for
WNV may occur in patients recently vaccinated for, or infected with, related flaviviruses (i.e., yellow fever, Japanese Encephalitis,
dengue)

Patient samples obtained at hospital labs in Delaware should be sent to the Delaware Public Health Laboratory (DPHL) for confirmatory
testing after consultation with the Bureau of Epidemiology. Please contact DPHL at 302- 223-1520 for courier pickup.

Healthcare providers may also request WNV testing from commercial laboratories. These results should be confirmed at DPHL after
consultation with the Bureau of Epidemiology. Please contact DPHL at 302- 223-1520 for courier pickup.

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